If you’re just getting started and plan to add to the account regularly, start an account with Vanguard in their 500 Index fund (ticker: VFINX). It matches the S&P 500, has the smallest expense ratio of any fund, and is a solid core holding. While you’re building your account there, start researching other mutual funds and stocks. You’ll want to look at small cap funds, mid cap funds, international funds, and sector funds. Always stick with no-load funds and pay particular attention to Morningstar ratings. When the Index 500 account passes $10k, then start diversifying into other funds or stocks. Stock investing will take considerably more work and time than fund investing, so keep that in mind.

If your employer offers a 401k, go with that, especially if there is an employer match.